2024-02-17

Last modified: 2024-02-17 20:41:00

• Busyboard
• Composite kitchen worktop offcuts
• Micro milling machine

Busyboard

Making the conrod with the CNC router was a success:

I used clamping broadly the same as yesterday, i.e. bolted at both ends. It did shift around a bit as the material was removed, but not too bad. Definitely acceptable for this purpose.

I wore some ear defenders which makes the CNC router a lot less unpleasant.

Composite kitchen worktop offcuts

I did some tests with an offcut of kitchen worktop:

The material is 25mm thick, and the best way I found to tap threads was:

• M8: drill to 6.5mm, tap up to the middle-sized tap
• M10: drill to 8.5mm, tap up to the middle-sized tap

I drilled with the pillar drill and tapped with a cordless drill.

8.5mm is the correct drill for M10. 6.5mm is slightly under-sized for M8, but the next size up I have is 7.0mm, which is over-sized. In both cases I was unable to insert a bolt if I used only the smallest-sized tap, so the middle-sized one is the smallest possible.

For both M8 and M10 threads tapped as above, with a full 25mm of engagement, I was not able to strip the thread with either the impact driver or a spanner, but I was able to strip it relatively easily using the breaker bar.

For both M8 and M10 threads, I found that if I tapped all the way to the largest-sized tap then the threads stripped with the impact driver.

I found that the material chips out very easily.

I hit it with a hammer and it did not shatter.

So this material may be suitable for my purposes. It's not ideal that it chips out and strips threads so easily, but if I'm careful I might get away with it, and it is very much a bonus that it is free.

Pieces I have are:

• 960mm * 460mm (some test cuts along the length of it, up to about 80mm in from one edge, so 960mm * 380mm good, but the rest potentially still usable)
• 600mm * 500mm
• 600mm * 400mm
• 470mm * 260mm
• 270mm * 230mm
• 270mm * 230mm (again)

And parts I will need are:

• base plate
• table
• 2x gantry legs
• gantry
• Z axis backplate

I can probably machine it with the CNC router, or, for pieces that are too big, definitely with the tablesaw, circular saw, or handheld router.

Potentially I could double up the material if I have enough, joining pieces together with bolts and epoxy.

Micro milling machine

If I use the worktop offcuts for the frame, and I dismantle the existing milling machine to get motors, drivers, ballscrews/ballnuts, etc., and I use the 1.5kW spindle that I already have, and the VFD that I have in the router cabinet, then to start making chips with the new machine I only need to buy:

• linear rails/bearings
• shaft couplers
• ballscrew support bearings
• spindle motor clamp

Which I reckon would be maybe £150 for linear rails/bearings if I buy cheap ones on Amazon, £40 for shaft couplers, £60 for ballscrew bearings, and £30 for a spindle motor clamp, = £280. And if I then find that I'm dissatisfied with the ballscrews/ballnuts from the old machine then I can replace them at a later date, already with knowledge that the machine is going to work etc. and I'm not spending thousands upfront.

I should do some CAD to actually design the machine, and then start making the parts that I can start making, and then buy whatever I need to buy.